A ground lug is a mechanical device, usually a piece of formed copper sheet metal, with a clamping screw that is attached to a piece of electrical equipment. A typical purpose of the ground lug is to allow electrical equipment to be connected to an external wire that is electrically attached to earth-ground.
A problem with conventional ground lugs is they only have two entry ports, thus allowing only two directions for a wire to enter and be secured by the ground lug. This two-port limitation is problematic during installation because an earth-ground wire is typically large in size and supports a solid core wire, which is not easily routed in an intricate manner. Additionally, any bends that are made to the wire are potential failure areas, since the wire tends to crack fully or partially at the bend. If the wire cracks fully at the bend, there will be a loss of electrical continuity and the ground path will not be completed. If the wire partially cracks, and there is no indication of a loss of continuity, the reduced cross section of the wire will cause higher electrical resistance. As a result, the ground path is compromised in its ability to function, generally resulting in a failure to the electrical equipment that is was protecting.